netdev - Re: [PATCH bpf-next V3 0/6] bpf: New approach for BPF MTU handling

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Message-ID: <20201009093319.6140b322@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 9 Oct 2020 09:33:19 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        maze@...gle.com, lmb@...udflare.com, shaun@...era.io,
        Lorenzo Bianconi <lorenzo@...nel.org>, marek@...udflare.com,
        John Fastabend <john.fastabend@...il.com>,
        eyal.birger@...il.com
Subject: Re: [PATCH bpf-next V3 0/6] bpf: New approach for BPF MTU handling

On Thu, 08 Oct 2020 16:08:57 +0200 Jesper Dangaard Brouer wrote:
> V3: Drop enforcement of MTU in net-core, leave it to drivers

Sorry for being late to the discussion.

I absolutely disagree. We had cases in the past where HW would lock up
if it was sent a frame with bad geometry.

We will not be sprinkling validation checks across the drivers because
some reconfiguration path may occasionally yield a bad packet, or it's
hard to do something right with BPF.